Another solar newbie needs help please.

[StevePinExeter]

Hello everyone,

Having a weird problem and am hoping someone here might have some insight on what is going wrong… Here is the full story. My name is Steve and I live in Exeter, New Hampshire. I set up the very small little system described here in order to dip my toe into the water of solar power and also to get some experience before putting solar lights in a small camper I plan to build over the next few years.

So, I set up a small system to put lights in my shed and also to power a small number of 12v LED landscape lights. The power requirements of both are extremely modest. The shed lights aren’t used for long or very often and the landscape lights are little more then fairy lighting. I started with buying a 50-Watt 12v Polycrystalline Solar Panel from the Home Depot; a 12V 20AH Sealed Lead Acid (SLA) AGM Rechargeable Maintenance Free Battery; and one of those dirt cheap charge controllers, a MOHOO Solar Charge Controller, 30A Solar Charger Controller, 12V/24V. No inverter, everything I am running is 12v DC.

I put the panel on the south facing roof of my shed, it is in full sunlight pretty much all day. The controller’s directions were horribly translated from Chinese but it was fairly straight forward. I hooked up the battery first, then the panel, then the load; (a cheap automotive fuse box with one fuse feeding two LED 12 volt light bulbs in the shed on a manual switch and a second fuse going to the landscape lights with a photo "on at dusk,off at dawn" switch) The controller correctly recognized my battery and panel types, the default setting looked OK to me.

Everything worked great and just as I hoped it would and this lasted for several months.

Then… one day a few hours after sunset I noticed the landscape lights were blinking. My first assumption was the photo switch was malfunctioning but when I went out the shed the lights on the manual switch were blinking too. I figured it was feedback or something from the bad switch so I turned the system off, pulled the fuse to the landscape lights and went back in the house. The next day I turned the system back on and that evening, just to confirm the problem was the photo switch, I turned on the shed lights with the landscape lights still disconnected. A few hours later the shed lights were blinking again.

So next I figured the problem was the cheap controller and I followed the instructions to re-set it; discounted the load, then the panel, then the battery. I let it sit overnight and then the next day connected the battery, then the panel, then the load. That evening a few hours after sunset all the lights were blinking, no improvement.

OK, so I decided the cheap control was on the fritz and ordered a replacement, a slightly better looking and slightly less cheap (but still pretty darn cheap) one like this: HUGOOME PWM Solar Charge Controller 30A, Compatible with Li, Sealed, Gel, Flooded Batteries, 12V/24V Solar Panel Battery Regulator. I followed the almost as badly translated instructions and hooked this one up the same way: Battery, Panel, Load. It correctly recognized both my battery type and panel and the default settings looked fine to me. That night, an hour or two after sunset BLINK, BLINK, BLINK, BLINK….
I shut it down and the following weekend physically disconnected EVERYTHING and started from scratch. This time I only connected the shed lights just in case a bad photo switch was still somehow being a problem. And, not by just pulling the fuse, the wires to the landscape lights aren’t even coming into the room anymore. I turned on the shed lights, waited about an hour or so and looked out…. BLINK, BLINK, BLINK, BLINK…. I have NO IDEA what to do next.

Any ideas what the heck could be causing this?

[SunEagle]

Chances are your load finally discharged the battery and the 50w panel did not fully recharge it. It happens a lot when someone underestimates their watt hour load for each day and if the panel will put back what is taken out. Then if you have a couple of cloudy days the panel will not put enough back into the battery so it slowly discharges to the point of failure.

My guess is that you will need a bigger battery and more panel wattage to charge it.

[chrisski]

I do think the battery died. from being to small and not enough panel, but without a good power audit, we'll never know. Here are some for me:

Battery Draws 12 Volts 2020 07 03.jpg
I have three LED strips on there. My bright 10' awning lights at 1 amp; a 2. bright white LED strip at .15 amps, and a 6' Led strip at .5 amps. There's also a some Puk lights at .45 amps each, and a set of puk lights at 1.4 amps.

A 50 watt panel at max can push those 3 amps into a battery. Although I may get 18 hours of sunshine in AZ now, only 7 of those provide the full 3 amps in the summer for 21 amps total, and in the winter that will only be 4 hours of sunshine providing the full amps for a total of 12 amps in a 10 hour long sunset to sunrise. That is not a lot. I live in the best case scenario with no rain to speak of and no clouds 300 days of the year. If you're in Seattle much worst.

So if you had two LED strips like on my awning lights, with a 6 hours of on time, that's only 12 amps with enough produced in the summer to make up for it each sunny day. A cloudy day in the summer may see that panel produce 7 amps or in the winter 4 amps. When this keeps up long enough, the battery dips below 50%, and that would happen even here in sunny AZ, when the one time a year when the clouds may interfere with production for three days in a row. Once it dips below 50%, the battery won't really reach full production again.

I don't know how many amps your bulbs pull, but I buy my LEDs from SuperBrightLEDs and most have accurate amp listings. At the store, the watt ratings seem realistic for the few I checked. With a 20 AH battery, any series of bulbs you leave on would be a real draw on this battery.

[robbyg]

I kind of agree with SunEagle's assessment except I would have expected the lights to just dim out slowly since your using straight 12VDC to power the lights. For what your doing I would probably have gone with Lithium Batteries as they can take a lot more cycles and discharge a lot more power.

For what your doing I would have just gotten something like this for the Shed.

https://www.amazon.com/Light-Control-Outdoor-Lithium-Ion-Functions/dp/B08L5DPQ6K/ref=sr_1_18?dchild=1&keywords=solar%2Bbarn%2Blight&qid=1625798298&s=lawn-garden&sr=1-18&th=1

And these for the walkway:

https://www.amazon.com/product-reviews/B07WLKT2HZ/ref=cm_cr_unknown?ie=UTF8&filterByStar=four_star&reviewerType=all_reviews&pageNumber=1#reviews-filter-bar

[Mike90250]

LED's with an integral driver circuit, will do strange things as the voltage gets low.

[StevePinExeter]

Hi guys, thanks for so many quick responses. I know the battery and panel are small but the entire group of landscape lights draws less than half an amp. The shed lights draw a bit more but are rarely on for more than a minute or two a few times a week other than when I was using them for testing. If both charge controllers are to be believed the battery was normally getting charged to full and when it was't the controllers don't let the load come on. It seemed to me like they were both doing exactly what they were supposed to do to protect the battery... I don't think the battery should ever have been pulled down below 11.3 volts. The other day even while the lights were flashing the battery said it was putting out well over 13v. It is unquestionably a blink, not a flicker or dimming or pulsate. Very steady blink blink blink.

[SunEagle]

Hi guys, thanks for so many quick responses. I know the battery and panel are small but the entire group of landscape lights draws less than half an amp. The shed lights draw a bit more but are rarely on for more than a minute or two a few times a week other than when I was using them for testing. If both charge controllers are to be believed the battery was normally getting charged to full and when it was't the controllers don't let the load come on. It seemed to me like they were both doing exactly what they were supposed to do to protect the battery... I don't think the battery should ever have been pulled down below 11.3 volts. The other day even while the lights were flashing the battery said it was putting out well over 13v. It is unquestionably a blink, not a flicker or dimming or pulsate. Very steady blink blink blink.

Well as Mike stated the drive for an LED will do some interesting things when the voltage is below it's desired value. Just like an incandescent bulb will dim when the voltage dips the LED may go out and then come back on as the voltage varies.

I still think your 20Ah battery is small and has been depleted even though you feel your loads are small. Sometimes it is the cheap CC that causes the issue but most times it is because the battery is too small for your loads. The battery dies slowly and becomes an issue after a short time. That is what happens after a while just like you have experienced.

[StevePinExeter]

Thanks guys, I am sure you're probably right and will try a new battery, if that seems to do the trick I will add another solar panel to keep the new battery charged up.

[SunEagle]

Thanks guys, I am sure you're probably right and will try a new battery, if that seems to do the trick I will add another solar panel to keep the new battery charged up.

Just remember you will need charging amps the equal about 1/10th the Amp Hour rating of your battery system.

[AWS]

Aren't you suppose to pull your load from the battery? I thought the load terminal on the controller was only for a meter or a very light load.. My controller doesn't even have a load terminal, just the the panel and battery terminals.

[SunEagle]

Aren't you suppose to pull your load from the battery? I thought the load terminal on the controller was only for a meter or a very light load.. My controller doesn't even have a load terminal, just the the panel and battery terminals.

Some of the Quality CC's have a high amp rated Load terminals. Most can only handle very small loads and will burn out quickly if over loaded. For those you need to come off the battery to power the loads.

[ewarnerusa]

Aren't you suppose to pull your load from the battery? I thought the load terminal on the controller was only for a meter or a very light load.. My controller doesn't even have a load terminal, just the the panel and battery terminals.

I was also thinking that the OP may have the lights wired to the "Load" output of the controller rather than to the batteries as they should be. 12V loads are nearly always wired directly to the batteries.

[Stephen123]

I put in Renogy solar panels <link removed> on the roof of my RV it was super easy to install and of high quality works well charges quickly. The electronics are sturdy and easy to adapt, the production from the panel was easy enough to power 2 laptops, phones and watches not to mention lights, fan, water pump, and friend's electronics. Crazy good panel and kept the deep cell battery over 85% for 2 straight weeks.

Mod note: Please no ads or links to other sites, thanks.